Attempts will be made to purify membrane immunoglobulin from lymphoid cells in order to extensively characterize the oligosaccharide units present in these membrane glycoproteins. Glycopeptides from membrane immunoglobulin will then be compared to glycopeptides from secretory immunoglobulin to determine if differences in carbohydrate moieties are present in these highly related antibody structures. Since the C micron 4 domain of membrane IgM is likely to be the region of the heavy chain interacting with the cell membrane, it too will be purified and analyzed for carbohydrate and amino acid sequences. In addition, the re-expression of nonglycosylated surface immunoglobulin will be further studied using the antibiotic tunicamycin which is known to inhibit glycosylation. Attempts will be made to define the overall role of glycosylation for the localization of membrane immunoglobulin in the plasma membrane and for the processing of secretory immunoglobulin prior to secretion.